1. Field of the Invention
This invention relates to fiber optics with particular reference to the focusing of distal objectives in long fiberscopes.
2. Description of the Prior Art
In flexible fiberscopes it is often desirable to be able to focus the distal objective remotely, i.e. from the proximal end or handle. This is usually accomplished with a sliding wire in a tubular guide as shown in exemplary U.S. Pat. No. 3,091,235. In long fiberscopes or when a fiberscope is coiled or bent sharply, friction within the tubular guide causes the inner wire to stick or bind and focusing is unreliable or inactivated.
In general, the amount of movement needed is very small, e.g. in the order of a few millimeters or less, and little force is needed to move the usually small and lightweight lenses and retaining barrel. Thus, a system capable of small precise movement is appropriate and, accordingly, it is a principal object of this invention to provide such a system.
It is a further object to accomplish the foregoing without proximal-to-distal mechanical connection in the fiberscope and in a manner affording positive lens focusing response independently of length and degree of flexing of the fiberscope.
Other objects and advantages of the invention will become apparent from the following description.